3. Enzymes Flashcards
What are examples of enzymes?
Lipase
Sucrase
Protease
How do enzymes catalyse a reaction?
Lower the activation energy by aligning reactants and stressing the bonds.
What is the Lock and Key theory?
Substrate complementary to active site. Substrate binds to active site making a enzyme substrate complex, aligning reactants and lowering activation energy. Products are formed.
What is induced fit theory?
Tertiary structure of active site not complementary to substrate so induced fit causes active site of enzyme to change shape. So enzyme substrate complex causes bond o form/break.
How does enzyme conc affect the rate of reaction?
Increase, increase RofR as more successful collisions between substrate and active site so more enzyme substrate complexes formed.
At point,substrate conc become limiting factor as not enough substrate.
How does substrate conc affect R of R ?
Increase ,increases RofR as more successful collisions between active site and substrate so more enzyme substrate complexes formed.
At point, all active site full as enzyme conc limiting factor.
How does temperature affect R of R?
Faster at high temp as more kinetic energy so more enzyme substrate complexes formed. Rate will slow until all substrate used up.
Active site Denatures as increase in KE breaks hydrogen bonds between R grops on amino acids, change shape active site so no longer complemetary to substrate. Fewer enzyme substrate complexes formed.
How does temperature denature active site?
Active site Denatures as increase in KE breaks hydrogen bonds between R grops on amino acids, change shape active site so no longer complemetary to substrate. Fewer enzyme substrate complexes formed.
How does pH affect Rof R and how does it become denatured?
Optimum pH has highest RofR
Denature at extreme pH as hydrogen/ionic bonds between R groups on amino acids break. Alters shape of active site less enzyme substrate complexes formed.
What is the formula if given the hydrogen ion to calculate pH?
PH= -log10 [H+]
(Use log10 button on calc)
What does a competitive inhibitor do?
Decrease rate of enzyme controlled reaction. - As inhibitor has similar shape to substrate. Binds to the active site, preventing enzyme substrate complexes forming.
Can be overcome by adding more substrate
What does a non competitive inhibitor do?
Reduce rate of enzymes controlled reaction.
- attaches to enzyme at site other than active site (allosteric site). Changes shape of tertiary structure of enzyme, changes shape active site. Active site no longer complementary, substrate cant bind, no enzyme substrate complexes formed.
Can’t be overcome by adding more substrate
What is an extracellular enzyme do?
Enzymes secreted by cells and catalyse reactions outside cell. (E.g. digestive enzymes)
What is an intercellular enzyme?
Enzymes produced and function inside cell.
What is a phosphorylation?
The addition of a phosphate group using a ATP.
Can be done to make them more reactive, change shape of tertiary structure so active site becomes complementary to substrate activating the enzyme.
